“Come! Come! We found more,” children shout, pulling a femur, a stretch of spine and a human skull from a pile of dusty rubble.

They start digging through the wreckage with their hands and pick out a singed vertebra. One small boy overturns a concrete brick and points to a murky stain. “Blood,” he says.

The children have gathered on the ground floor of a ruined building in the Damascus suburb of Tadamon, where blood-stained clothes decompose on the floor and smoke has stained the ceiling black.

“Over there is where they shot people,” a teenager says, pointing to a stretch of dirt road outside. “This is where they burned their bodies.”

Once a rebel stronghold, Tadamon was almost completely razed during 13 years of civil war. It became a killing field, where locals say civilians were systematically slaughtered by militias loyal to Bashar al-Assad.

Today, the extent of the horrors is only just being uncovered.